The invention relates to a weaving machine with control devices that rapidly correct the warp let-off speed of the individual sectional warp beams according to the differences in the warp tensions measured. A weaving machine of the type described is disclosed in. EP-PS 0 136 389. This reference describes a feeler member mounted between a fixed deflecting roll and the whip roll to measure the tension of a warp yarn sheet. The feeler member comprises a deflecting element and a leaf spring, which is fixed to the deflector roll. Because of the yarn forces, the deflecting element is deflected against the action of the leaf spring; this deflection is measured with a sensor.
This known weaving machine allows weaving from a plurality of sectional warp beams when there is a single continuous whip roll which remains parallel to the warp beam axis during pivoting. The warp let-off control device rests in other weaving machines on a special form of whip roll, in which a tension difference can be determined from an oblique position of the whip roll. The intermittent oblique position of the whip roll, however, causes a reduction in cloth quality.
In the case of the known feeler members with leaf springs there is another problem: it has been found in practice that in production engineering terms it is difficult for the spring constant of the leaf springs to remain within a sufficiently narrow tolerance range relative to the warp let-off control. Because of the wide divergence of the spring constant a special calibration must be performed for each feeler member. In terry looms with cloth control (see EP-A 0 350 446, FIG. 9), the forces acting on the feeler member at full beat-up and partial beat-up are very different. Here, therefore, the divergence of the spring constant proves particularly disadvantageous.